The purpose of the proposed project is to characterize the performance of female adolescents with FXS on tests of social cognition that vary in their demand on executive functions (EFs). The study was motivated by the growing evidence of specific impairments in both social cognition and EFs in individuals with FXS, beyond what can be accounted for by intellectual disability. These deficits are associated with, and may underlie, major social disability and caregiver burden for adolescents with FXS and their families, and knowledge in this area has implications for both clinical intervention and models of phenotype development. We have developed social cognition tasks that directly manipulate two aspects of EFs, working memory and inhibitory control. The tasks require on-line social information processing and were developed in collaboration with adolescents to reflect their daily social lives; thus they have face and ecological validity for the evaluation of social cognition in this age group. The tasks will be used to characterize social cognition performance in adolescents with FXS who have IQs of 75 or above. Scores will be compared to self- and parent perceptions of social behavior, to explore the relation of social cognition task scores to outcomes beyond the laboratory. Social cognitive skills play a critical role in peer-appropriate social behavior, and also may be required for the acquisition of culture-specific social knowledge. Thus, adolescents with developmental social deficits may experience not only impairments at the level of body structures and functions, but also limitations in social activities and restricted participation in social life. This may in turn produce a variety of negative effects on subjective well-being and health. Thus, the study of adolescent social cognition is important not only for theoretical reasons but as a public health issue. [unreadable] [unreadable] [unreadable]